Preparation of Ce-Ag bimetallic modified biochar composite for the efficient removal of sulfathiazole and its mechanism

Modified biochar (Ce-Ag-BC) was successfully prepared by using Camellia oleifera shell and doping with cerium (Ce) and silver (Ag). Through the results of BET, SEM, XRD , FTIR, and XPS, Ce and Ag were successfully embedded on biochar and participated in the sulfathiazole (STZ) adsorption. After being modified, high adsorption capacity of STZ on Ce-Ag-BC was observed. The maximum adsorption amount of STZ on Ce-Ag-BC was 261.84 mg/g, which was increased by more than six times compared to raw biochar (BC, 42.41 mg/g). The adsorption kinetics and isotherm on Ce-Ag-BC could be better fitted to pseudo-second-order kinetic and Langmuir isotherm model, respectively, indicating that the adsorption is mainly controlled by chemisorption and can be described as a monolayer process. The STZ adsorption process on Ce-Ag-BC is a spontaneously endothermic reaction. Besides, the adsorption mechanism on Ce-Ag-BC mainly involves pore filling, π-π interaction, hydrogen bonding , and electrostatic attraction.